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Path: /data/applications/aps/gallery/2.3-2/standard/htdocs/modules/netpbm/classes/ [ Home ]
File: NetPbmToolkit.class
<?php
/*
 * Gallery - a web based photo album viewer and editor
 * Copyright (C) 2000-2008 Bharat Mediratta
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or (at
 * your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA  02110-1301, USA.
 */

GalleryCoreApi::requireOnce('modules/core/classes/GalleryToolkit.class');

/**
 * A NetPBM version of GalleryToolkit
 * @package NetPbm
 * @subpackage Classes
 * @author Bharat Mediratta <bharat@menalto.com>
 * @version $Revision: 17580 $
 */
class NetPbmToolkit extends GalleryToolkit {

    /**
     * @see GalleryToolkit::getProperty
     */
    function getProperty($mimeType, $propertyName, $sourceFilename) {

	switch($propertyName) {
	case 'dimensions':
	    list ($ret, $width, $height) = $this->_getImageDimensions($mimeType, $sourceFilename);
	    if ($ret) {
		return array($ret,
			     null);
	    }
	    $results = array($width, $height);
	    break;

	default:
	    return array(GalleryCoreApi::error(ERROR_UNIMPLEMENTED), null);
	}

	return array(null, $results);
    }

    /**
     * @see GalleryToolkit::performOperation
     */
    function performOperation($mimeType, $operationName, $sourceFilename,
			      $destFilename, $parameters, $context=array()) {
	global $gallery;
	$platform =& $gallery->getPlatform();

	/* Check context for any operations that have been queued up.. */
	$outputMimeType = $mimeType;
	if (isset($context['netpbm.transform'])) {
	    $transform = $context['netpbm.transform'];
	    $mimeType = $context['netpbm.mime'];
	    $preserveMetaData = $context['netpbm.metadata'];
	    unset($context['netpbm.transform']);
	    unset($context['netpbm.mime']);
	    unset($context['netpbm.metadata']);
	} else {
	    $transform = array();
	    $preserveMetaData = true;
	}
	if (isset($context['width'])) {
	    $width = $context['width'];
	    $height = $context['height'];
	}

	/* Use context look-ahead to see if we can queue up parameters to use later.. */
	$queueIt = isset($context['next.toolkit']) && $context['next.toolkit'] == $this
	    && $operationName != 'compress' && $context['next.operation'] != 'compress';

	$usePercent = in_array($operationName, array('thumbnail', 'scale', 'resize'))
	    && (substr($parameters[0], -1) == '%'
		    || (isset($parameters[1]) && substr($parameters[1], -1) == '%'));

	if (!isset($width) && ($queueIt || $usePercent
		    || in_array($operationName, array('thumbnail', 'crop')))) {
	    list ($ret, $width, $height) =
		$this->_getImageDimensions($mimeType, $sourceFilename);
	    if ($ret) {
		$this->_deleteTempFiles($context);
		return array($ret, null, null);
	    }
	}

	if ($usePercent) {
	    /* Convert percentages to real image dimensions */
	    if (substr($parameters[0], -1) == '%') {
		$parameters[0] = (int)round($width * rtrim($parameters[0], '%') / 100);
	    }
	    if (isset($parameters[1]) && substr($parameters[1], -1) == '%') {
		$parameters[1] = (int)round($height * rtrim($parameters[1], '%') / 100);
	    }
	}

	switch($operationName) {
	case 'thumbnail':
	    /* Don't enlarge images for a thumbnail */
	    $preserveMetaData = false;
	    if ($width <= $parameters[0] && $height <= $parameters[0]) {
		break;
	    } else {
		/* fall through to scale */
	    }

	case 'scale':
	    $ysize = empty($parameters[1]) ? $parameters[0] : $parameters[1];
	    $transform[] = array($this->_pnmCmd('pnmscale'),
				 '--quiet', '-xysize', $parameters[0],
				 $ysize);
	    if (isset($width)) {
		list ($width, $height) = GalleryUtilities::scaleDimensionsToFit(
		    $width, $height, $parameters[0], $ysize);
	    }
	    break;

	case 'resize':
	    $transform[] = array($this->_pnmCmd('pnmscale'),
				 '--quiet', '-xsize', $parameters[0], '-ysize', $parameters[1]);
	    if (isset($width)) {
		list ($width, $height) = GalleryUtilities::scaleDimensionsToFit(
					 $width, $height, $parameters[0], $parameters[1]);
	    }
	    break;

	case 'rotate':
	    switch($parameters[0]) {
	    case -90:
		$flipArgument = "-ccw";
		break;

	    case 90:
		$flipArgument = "-cw";
		break;

	    case -180:
	    case 180:
		$flipArgument = "-r180";
		break;

	    default:
		$this->_deleteTempFiles($context);
		return array(GalleryCoreApi::error(ERROR_BAD_PARAMETER, __FILE__, __LINE__,
				    "Bad rotation argument: $parameters[0]"), null, null);
	    }

	    $transform[] = array($this->_pnmCmd('pnmflip'), $flipArgument);
	    if (isset($width) && ($parameters[0] == 90 || $parameters[0] == -90)) {
		$tmp = $width;
		$width = $height;
		$height = $tmp;
	    }
	    break;

	case 'crop':
	    /* Crop is in percentages so we have to know the dimensions of the input file */
	    $transform[] = array($this->_pnmCmd('pnmcut'),
				 round(($parameters[0] / 100) * $width),
				 round(($parameters[1] / 100) * $height),
				 $width = round(($parameters[2] / 100) * $width),
				 $height = round(($parameters[3] / 100) * $height));
	    break;

	case 'convert-to-image/jpeg':
	    $outputMimeType = 'image/jpeg';
	    break;

	case 'composite':
	    $compositeOverlayPath = $gallery->getConfig('data.gallery.base') . $parameters[0];
	    $compositeOverlayMimeType = $parameters[1];
	    $compositeWidth = $parameters[2];
	    $compositeHeight = $parameters[3];
	    $compositeAlignmentType = $parameters[4];
	    $compositeAlignX = $parameters[5];
	    $compositeAlignY = $parameters[6];

	    /*
	     * Create temporary files, composite may need to be decomposed into
	     * rgb & alpha images
	     */
	    $tmpDir = $gallery->getConfig('data.gallery.tmp');
	    $tmpOverlay = $platform->tempnam($tmpDir, 'npbm_');
	    if (empty($tmpOverlay)) {
		/* This can happen if the $tmpDir path is bad */
		return array(GalleryCoreApi::error(ERROR_BAD_PATH, __FILE__, __LINE__,
						  "Could not create tmp file in '$tmpDir'"),
			     null, null);
	    }
	    $context['netpbm.tmp'][] = $tmpOverlay;

	    $tmpAlpha = $platform->tempnam($tmpDir, 'npbm_');
	    if (empty($tmpAlpha)) {
		/* This can happen if the $tmpDir path is bad */
		return array(GalleryCoreApi::error(ERROR_BAD_PATH, __FILE__, __LINE__,
						  "Could not create tmp file in '$tmpDir'"),
			     null, null);
	    }
	    $context['netpbm.tmp'][] = $tmpAlpha;

	    switch ($compositeOverlayMimeType) {
	    case 'image/png':
		$useAlpha = 1;
		$getOverlayCmd = array($this->_pnmCmd('pngtopnm'),
				       $compositeOverlayPath,
				       '>',
				       $tmpOverlay);
		$getAlphaCmd   = array($this->_pnmCmd('pngtopnm'),
				       '-alpha',
				       $compositeOverlayPath,
				       '>',
				       $tmpAlpha);
		break;

	    case 'image/jpeg':
	    case 'image/pjpeg':
		$useAlpha = 0;
		$getOverlayCmd = array($this->_pnmCmd('jpegtopnm'),
				       $compositeOverlayPath,
				       '>',
				       $tmpOverlay);
		break;

	    case 'image/gif':
		$useAlpha = 1;
		$getOverlayCmd = array($this->_pnmCmd('giftopnm'),
				       '-alphaout=' . $tmpAlpha,
				       $compositeOverlayPath,
				       '>',
				       $tmpOverlay);
		break;

	    case 'image/tiff':
		/*
		 * This is only because my decomposed alpha was "all black", and
		 * made it seem like it wasn't doing anything
		 */
		$useAlpha = 0;
		$getOverlayCmd = array($this->_pnmCmd('tifftopnm'),
				       '-alphaout=' . $tmpAlpha,
				       $compositeOverlayPath,
				       '>',
				       $tmpOverlay);
		break;
	    default:
		$this->_deleteTempFiles($context);
		return array(GalleryCoreApi::error(ERROR_UNIMPLEMENTED, __FILE__, __LINE__,
		    "mimeType not handled: $compositeOverlayMimeType"), null, null);
	    }

	    /* Execute commands */
	    list ($success, $output) = $platform->exec(array($getOverlayCmd));
	    if (!$success) {
		$this->_deleteTempFiles($context);
		return array(GalleryCoreApi::error(ERROR_UNKNOWN, __FILE__, __LINE__,
				    "Could not get/convert/extract overlay"), null, null);
	    }
	    if (isset($getAlphaCmd)) {
		list ($success, $output) = $platform->exec(array($getAlphaCmd));
		if (!$success) {
		    $this->_deleteTempFiles($context);
		    return array(GalleryCoreApi::error(ERROR_UNKNOWN, __FILE__, __LINE__,
					"Could not get/convert/extract alpha"), null, null);
		}
	    }
	    $pnmcomp = array($this->_pnmCmd('pnmcomp'));

	    switch ($compositeAlignmentType) {
	    case 'top-left': /* Top - Left */
		$pnmcomp[] = '-align=left';
		$pnmcomp[] = '-valign=top';
		break;

	    case 'top': /* Top */
		$pnmcomp[] = '-align=center';
		$pnmcomp[] = '-valign=top';
		break;

	    case 'top-right': /* Top - Right */
		$pnmcomp[] = '-align=right';
		$pnmcomp[] = '-valign=top';
		break;

	    case 'left': /* Left */
		$pnmcomp[] = '-align=left';
		$pnmcomp[] = '-valign=middle';
		break;

	    case 'center': /* Center */
		$pnmcomp[] = '-align=center';
		$pnmcomp[] = '-valign=middle';
		break;

	    case 'right': /* Right */
		$pnmcomp[] = '-align=right';
		$pnmcomp[] = '-valign=middle';
		break;

	    case 'bottom-left': /* Bottom - Left */
		$pnmcomp[] = '-align=left';
		$pnmcomp[] = '-valign=bottom';
		break;

	    case 'bottom': /* Bottom */
		$pnmcomp[] = '-align=center';
		$pnmcomp[] = '-valign=bottom';
		break;

	    case 'bottom-right': /* Bottom Right */
		$pnmcomp[] = '-align=right';
		$pnmcomp[] = '-valign=bottom';
		break;

	    case 'manual':
		/* Use the alignments we received */
		if (!isset($width)) {
		    list ($ret, $width, $height) =
			$this->_getImageDimensions($mimeType, $sourceFilename);
		    if ($ret) {
			$this->_deleteTempFiles($context);
			return array($ret, null, null);
		    }
		}

		/* Convert from percentages to pixels */
		$compositeAlignX = (int)($compositeAlignX / 100 * ($width - $compositeWidth));
		$compositeAlignY = (int)($compositeAlignY / 100 * ($height - $compositeHeight));

		/* Clip to our bounding box */
		$compositeAlignX = min($compositeAlignX, $width - $compositeWidth);
		$compositeAlignX = max(0, $compositeAlignX);
		$compositeAlignY = min($compositeAlignY, $height - $compositeHeight);
		$compositeAlignY = max(0, $compositeAlignY);

		$pnmcomp[] = '-xoff=' . $compositeAlignX;
		$pnmcomp[] = '-yoff=' . $compositeAlignY;
		break;

	    default:
		$this->_deleteTempFiles($context);
		return array(GalleryCoreApi::error(ERROR_BAD_PARAMETER, __FILE__, __LINE__,
		    "Unknown composite alignment type: $compositeAlignmentType"), null, null);
	    }

	    if ($useAlpha) {
		$pnmcomp[] = '-alpha=' . $tmpAlpha;
	    }

	    $pnmcomp[] = $tmpOverlay;
	    $transform[] = $pnmcomp;

	    break; /* case composite */

	case 'compress':
	    $targetSize = $parameters[0];
	    $fileSize = $platform->filesize($sourceFilename) >> 10; /* Size in KB */
	    if ($fileSize <= $targetSize) {
		break;
	    }
	    /* Use module quality parameter as initial guess */
	    list ($ret, $quality) =
		GalleryCoreApi::getPluginParameter('module', 'netpbm', 'jpegQuality');
	    if ($ret) {
		return array($ret, null, null);
	    }
	    $maxQuality = 100;
	    $minQuality = 5;
	    do {
		$ret = $this->_transformImage($mimeType, array(), $sourceFilename,
					      $destFilename, $outputMimeType, true, $quality);
		if ($ret) {
		    return array($ret, null, null);
		}
		clearstatcache();
		$fileSize = $platform->filesize($destFilename) >> 10;
		if ($fileSize >= $targetSize) {
		    $maxQuality = $quality;
		}
		if ($fileSize <= $targetSize) {
		    $minQuality = $quality;
		}
		$quality = round(($minQuality + $maxQuality) / 2);
	    } while ($maxQuality - $minQuality > 2 &&
		     abs(($fileSize - $targetSize) / $targetSize) > 0.02);
	    return array(null, $outputMimeType, $context);

	default:
	    $this->_deleteTempFiles($context);
	    return array(GalleryCoreApi::error(ERROR_UNSUPPORTED_OPERATION, __FILE__, __LINE__,
					      "$operationName $outputMimeType"), null, null);
	}

	if (isset($width)) {
	    $context['width'] = $width;
	    $context['height'] = $height;
	}

	if (($queueIt || (empty($transform) && $outputMimeType == $mimeType)) &&
		$sourceFilename != $destFilename) {
	    if (!$platform->copy($sourceFilename, $destFilename)) {
		$this->_deleteTempFiles($context);
		return array(GalleryCoreApi::error(ERROR_PLATFORM_FAILURE),
			     null, null);
	    }
	}

	/*
	 * Use context look-ahead to see if we can queue up these parameters
	 * to include in a later operation..
	 */
	if ($queueIt) {
	    $context['netpbm.transform'] = $transform;
	    $context['netpbm.mime'] = $mimeType;
	    $context['netpbm.metadata'] = $preserveMetaData;
	    return array(null, $outputMimeType, $context);
	}

	if (!empty($transform) || $outputMimeType != $mimeType) {
	    $ret = $this->_transformImage($mimeType, $transform, $sourceFilename,
					  $destFilename, $outputMimeType, $preserveMetaData);
	}

	/*
	 * We still need to delete the temporary overlay/alphamask for compositing
	 * before, possibly, returning an error
	 */
	$this->_deleteTempFiles($context);
	if (isset($ret) && $ret) {
	    return array($ret, null, null);
	}

	return array(null, $outputMimeType, $context);
    }

    /**
     * Delete temp files used by composite operation
     */
    function _deleteTempFiles(&$context) {
	if (!empty($context['netpbm.tmp'])) {
	    global $gallery;
	    $platform =& $gallery->getPlatform();
	    foreach ($context['netpbm.tmp'] as $tmpFile) {
		if ($platform->file_exists($tmpFile)) {
		    @$platform->unlink($tmpFile);
		}
	    }
	    unset($context['netpbm.tmp']);
	}
    }

    /**
     * @see GalleryToolkit::getImageDimensions
     */
    function _getImageDimensions($mimeType, $filename) {
	global $gallery;

	/*
	 * Run it through PHP first, it's faster and more portable.  If it runs
	 * afoul of open_basedir it'll return false and we can try NetPBM.
	 */
	$platform =& $gallery->getPlatform();
	$results = $platform->getimagesize($filename);
	if (($results != false) &&
	    (($results[0] > 1) && ($results[1] > 1))) {
	    return array(null, $results[0], $results[1]);
	}

	if ($mimeType == 'image/x-portable-pixmap') {
	    $cmd[] = array($this->_pnmCmd('pnmfile'), '--allimages', $filename);
	} else {
	    list ($ret, $convertToPnmCmd) = $this->_convertToPnmCmd($mimeType, $filename);
	    if ($ret) {
		return array($ret, null, null);
	    }

	    $cmd = array();
	    if (!empty($convertToPnmCmd)) {
		$cmd[] = $convertToPnmCmd;
	    }
	    $cmd[] = array($this->_pnmCmd('pnmfile'), '--allimages');
	}

	list ($ret, $output) = $this->_exec($cmd);
	if ($ret) {
	    return array($ret, null, null);
	}

	foreach ($output as $line) {
	    if (ereg('([0-9]+) by ([0-9]+)', $line, $regs)) {
		return array(null, $regs[1], $regs[2]);
	    }
	}

	return array(GalleryCoreApi::error(ERROR_TOOLKIT_FAILURE), null, null);
    }

    /**
     * Do the given transform on the source image
     *
     * @param string $mimeType a mime type
     * @param array $command the command(s) to execute
     * @param string $sourceFilename the path to a source file
     * @param string $destFilename the path to a destination file
     * @param string $outputMimeType
     * @param boolean $preserveMetaData (optional) whether to use jhead to preserve exif data
     * @param string $jpegQuality (optional) override module setting for jpeq quality
     * @return GalleryStatus a status code
     */
    function _transformImage($mimeType, $command, $sourceFilename, $destFilename, $outputMimeType,
			     $preserveMetaData=true, $jpegQuality=null) {
	global $gallery;
	$platform =& $gallery->getPlatform();

	/* Figure out our convert-to-pnm command */
	list ($ret, $convertToPnmCmd) = $this->_convertToPnmCmd($mimeType, $sourceFilename);
	if ($ret) {
	    return $ret;
	}

	/* Get a temp file name and figure out our convert-from-pnm command */
	$tmpDir = $gallery->getConfig('data.gallery.tmp');
	$tmpFilename = $platform->tempnam($tmpDir, 'npbm_');
	if (empty($tmpFilename)) {
	    /* This can happen if the $tmpDir path is bad */
	    return GalleryCoreApi::error(ERROR_BAD_PATH);
	}

	list ($ret, $convertFromPnmCmd) =
	    $this->_convertFromPnmCmd($outputMimeType, $tmpFilename, $jpegQuality);
	if ($ret) {
	    @$platform->unlink($tmpFilename);
	    return $ret;
	}

	/* Do the conversion */
	$command[] = $convertFromPnmCmd;

	if (!empty($convertToPnmCmd)) {
	    array_unshift($command, $convertToPnmCmd);
	} else {
	    /*
	     * The source file was PPM already so we have no conversion command.  Attach the file as
	     * input to the first command in the chain.  If the first command is in the middle of
	     * a sequence, we can just add the filename to the end of the command.  If it's at
	     * the end of the sequence, then we're redirecting output to a file so we have to add
	     * the input file before the '>' redirect.
	     */
	    for ($i = 0; $i < sizeof($command[0]); $i++) {
		if ($command[0][$i] == '>') {
		    array_splice($command[0], $i, 0, $sourceFilename);
		    $spliced = true;
		    break;
		}
	    }
	    if (!$spliced) {
		$comand[0][] = $sourceFilename;
	    }
	}

	list ($ret, $output) = $this->_exec($command);
	if ($ret) {
	    @$platform->unlink($tmpFilename);
	    return $ret;
	}

	/* Use jhead to preserve EXIF metadata for some mime types */
	if ($preserveMetaData && ($mimeType == 'image/jpeg' || $mimeType == 'image/pjpeg')) {
	    list ($ret, $jheadPath) =
		GalleryCoreApi::getPluginParameter('module', 'netpbm', 'jheadPath');
	    if ($ret) {
		@$platform->unlink($tmpFilename);
		return $ret;
	    }

	    if (!empty($jheadPath)) {
		$cmd = array($jheadPath . 'jhead', '-te', $sourceFilename, $tmpFilename);
		list ($ret, $stdout, $stderr) = $this->_exec(array($cmd));
		if ($ret) {
		    @$platform->unlink($tmpFilename);
		    return GalleryCoreApi::error(ERROR_TOOLKIT_FAILURE);
		}
	    }
	}

	$success = $platform->rename($tmpFilename, $destFilename);
	if (!$success) {
	    @$platform->unlink($tmpFilename);
	    return GalleryCoreApi::error(ERROR_PLATFORM_FAILURE, __FILE__, __LINE__,
					"Failed renaming $tmpFilename -> $destFilename");
	}
	$platform->chmod($destFilename);

	return null;
    }

    /**
     * Generate the correct command to convert an image type to PNM.
     *
     * @param string $mimeType
     * @param string $filename the path to an image file
     * @return array GalleryStatus a status code,
     *               array 1 or more string commands
     */
    function _convertToPnmCmd($mimeType, $filename) {
	global $gallery;

	switch($mimeType) {
	case 'image/png':
	    $cmd = $this->_pnmCmd('pngtopnm');
	    break;

	case 'image/jpeg':
	case 'image/pjpeg':
	    $cmd = $this->_pnmCmd('jpegtopnm');
	    break;

	case 'image/gif':
	    $cmd = $this->_pnmCmd('giftopnm');
	    break;

	case 'image/tiff':
	    $cmd = $this->_pnmCmd('tifftopnm');
	    break;

	case 'image/bmp':
	    $cmd = $this->_pnmCmd('bmptopnm');
	    break;

	case 'image/x-portable-pixmap':
	    $cmd = '';
	    break;

	default:
	    return array(GalleryCoreApi::error(ERROR_UNSUPPORTED_FILE_TYPE,
		__FILE__, __LINE__, 'Unsupported file type: ' . $mimeType), null);
	}

	if (!empty($cmd)) {
	    return array(null, array($cmd, '--quiet', $filename));
	} else {
	    return array(null, array());
	}
    }

    /**
     * Generate the correct command to convert an image type from PNM.
     *
     * @param string $mimeType
     * @param string $filename the path to an image file
     * @param string $jpegQuality (optional) override module setting for jpeg quality
     * @return array GalleryStatus a status code,
     *               array 1 or more string commands
     */
    function _convertFromPnmCmd($mimeType, $filename, $jpegQuality=null) {
	global $gallery;

	if (!isset($jpegQuality)) {
	    list ($ret, $jpegQuality) =
		GalleryCoreApi::getPluginParameter('module', 'netpbm', 'jpegQuality');
	    if ($ret) {
		return array($ret, null);
	    }
	}

	switch($mimeType) {
	case 'image/png':
	    $cmd = array($this->_pnmCmd('pnmtopng'),
			 '>',
			 $filename);
	    break;

	case 'image/pjpeg':
	case 'image/jpeg':
	    $cmd = array($this->_pnmCmd('pnmtojpeg'),
			 '--quality=' . $jpegQuality,
			 '>',
			 $filename);
	    break;

	case 'image/gif':
	    $cmd = array(array($this->_pnmCmd('ppmquant'),
			       256),
			 array($this->_pnmCmd('ppmtogif'),
			       '>',
			       $filename));
	    break;

	case 'image/tiff':
	    $cmd = array($this->_pnmCmd('pnmtotiff'),
			 '>',
			 $filename);
	    break;

	case 'image/bmp':
	    $cmd = array(array($this->_pnmCmd('ppmquant'),
			       256),
			 array($this->_pnmCmd('ppmtobmp'),
			       '>',
			       $filename));
	    break;

	case 'image/x-portable-pixmap':
	    $cmd = null;
	    break;

	default:
	    return array(GalleryCoreApi::error(ERROR_UNSUPPORTED_FILE_TYPE), null);
	}

	return array(null, $cmd);
    }

    /**
     * Execute the command.  Flatten the command array first.
     * @param array $cmdArray
     * @return array GalleryStatus a status code
     *               string stdout output, string stderr output
     * @access private
     */
    function _exec($cmdArray) {
	global $gallery;

	$cmdArray = $this->_extractCommands($cmdArray);
	$platform =& $gallery->getPlatform();

	list ($success, $stdout, $stderr) = $platform->exec($cmdArray);
	if (!$success) {
	    return array(GalleryCoreApi::error(ERROR_TOOLKIT_FAILURE), null, null);
	}

	return array(null, $stdout, $stderr);
    }

    /**
     * Return the full path to the NetPBM command
     *
     * @param string $cmd a netpbm command (eg. "giftopnm")
     * @access private
     */
    function _pnmCmd($cmd) {
	global $gallery;
	$platform =& $gallery->getPlatform();

	list ($ret, $netPbmPath) = GalleryCoreApi::getPluginParameter('module', 'netpbm', 'path');
	if ($ret) {
	    /* TODO: This method is expected to return string */
	    return $ret;
	}

	if (in_array($cmd, array('pnmtojpeg', 'bmptopnm', 'pnmcomp'))) {
	    list ($ret, $cmd) = GalleryCoreApi::getPluginParameter('module', 'netpbm', $cmd);
	    if ($ret) {
		/* TODO: This method is expected to return string */
		return $ret;
	    }
	}

	return $netPbmPath . $cmd;
    }

    /**
     * Extract a single array of commands from a multilevel array of commands
     *
     * The command array may wind up being multilevel, eg:
     *
     * array(
     *   array('cmd', 'args'),
     *   array('cmd', 'args'),
     *   array(
     *     array('cmd', 'args'),
     *     array('cmd', 'args')
     *   ),
     * )
     *
     * Extract the commands as a single level array:
     *
     * array(
     *   array('cmd', 'args'),
     *   array('cmd', 'args'),
     *   array('cmd', 'args'),
     *   array('cmd', 'args')
     * )
     *
     * While maintaining the order.
     *
     * @param array $cmdArray a multilevel set of commands
     * @param int $level (unused?)
     * @return array a single level set of commands
     */
    function _extractCommands($cmdArray, $level=0) {
	$results = array();
	$arrayElements = 0;
	foreach (array_values($cmdArray) as $cmd) {
	    if (is_array($cmd)) {
		$results = array_merge($results, $this->_extractCommands($cmd, $level+1));
		$arrayElements++;
	    } else {
		array_push($results, $cmd);
	    }
	}

	if ($arrayElements == count($cmdArray)) {
	    return $results;
	} else {
	    return array($results);
	}
    }
}
?>